1. Field of Invention
This invention relates to remotely controlled illumination, and specifically to remote control of illumination via modulated light of a flashlight.
2. Description of Prior Art
Outdoor lighting traditionally consists of light fixtures powered by AC mains, mounted to outside walls, and activated either by wall-mounted switches or co-located motion sensors. These methods serve admirably for areas in the near proximity of a house or other structure connected to AC power such as a garage, but leave areas beyond the reach of the structure-mounted lighting in darkness.
With the advent of energy efficient LEDs and economical photo-electric power cells, self-contained solar-powered lighting systems have become popular. However, because of the limited solar charging energy available each day, and the economical limits of storage battery capacity, these systems provide just small circles of dim illumination close to the ground, sufficient for marking walkways, but little else. The dim output is necessary since the stored energy of the batteries must last for an extended period of time. Most battery-powered lighting systems are outfitted with a light sensor that detects the onset of darkness and activates the unit, which to be useable, must then operate for some multiple of hours. Even using energy efficient LEDs as a light source, the available instantaneous power must be extremely limited such that operation can be meted out for the necessary entire period.
The goal would be to activate the lighting unit just when actually needed, which for most practical instances would be for just a few minutes. If only needed for three minutes of use, the lighting device could deliver one hundred times as much power to the illuminating LEDs than if the power were required to last continuously for five hours.
One method to activate the lighting unit momentarily would be via motion detection. However, outdoor motion detectors are notorious for spurious tripping, whether by pets, nighttime animals, wind-blown foliage, etc., and whereas this is a minor annoyance when the light source is powered by AC mains, the false trips would quickly deplete the lighting unit's batteries, leaving the device useless when actually needed.
Another method would be to use radio control such as is used for opening garage doors. U.S. patent application 2010/0,295,457 A1 and European Patent 0734197 describe the use of wireless control of indoor light fixtures, while U.S. patent application 2008/0,211,412 A1 and European Patent 2522900 A1 describe the use of wireless control for outdoor battery-powered lighting systems. However, unlike a garage door, of which there is typically just one, outdoor lighting systems typically consist of multiple units dispersed around an area, and it would be disadvantageous to activate them all simultaneously, since those units not actually usefully activated would be needlessly dissipating their power storage.
Infrared energy could be focused and beamed in order to activate individual targeted lighting units, however since the energy is invisible, aiming the beam is difficult and only approximate. European Patent 0734197 describes using a visible laser to aid in aiming a beam to control indoor overhead fixtures, but laser technology is relatively expensive.
Better than the expense of a laser would be to use the growing application of visible light communication (VLC), whereby control communication is achieved using the same energy-efficient LEDs as is deployed in the outdoor light systems themselves. Examples of forerunners of this technology can be found in U.S. Pat. Nos. 5,412,284 and 4,153,860 which use photo-sensors to detect static light for controlling Christmas lights, and U.S. Pat. No. 4,629,941, which activates security lights by car headlights. U.S. Pat. No. 4,048,596 describes controlling a television by using two differential photocell devices for distinguishing a flashlight beam.
More recent examples of VLC use in lighting systems are European Patent 2208395 B1, which uses organic LEDs to both source illumination and receive control information, and U.S. Pat. No. 8,554,084, U.S. Pat. No. 8,521,035, and U.S. patent applications 2009/0129782, and 2008/0185969, which all use information communicated from the fixed illumination source to a remote device, i.e., in the opposite direction from that needed to the light source as required to selectively activate outdoor lighting units.
VLC techniques could potentially be used to selectively enable outdoor lighting units. Further, not only would it be advantageous to use cost-effective VLC technology to activate outdoor lighting units, but it would be additionally useful if the VLC control communication source could be integrated with a device that would already naturally accompany a nighttime excursion situation.